A Spine-Specific Phased Array for Transvertebral Ultrasound Therapy: Design and Simulation

Area of Science:

• Medical Imaging and Ultrasound
• Biomedical Engineering
• Acoustics

Background:

• Transspine ultrasound focusing faces challenges due to the complex geometry of the human spine.
• Developing effective focused ultrasound therapies for spinal cord diseases requires precise targeting within the spinal canal.

Purpose of the Study:

• To design and simulate the performance of two novel spine-specific phased arrays for sonicating targets within the thoracic spinal canal.
• To achieve efficient and controlled ultrasound focusing in the spinal canal.

Main Methods:

• Designed two 256-element, 500 kHz phased arrays: a four-component array and a two-component adaptive focusing array.
• Utilized multi-layered ray acoustics simulation to evaluate mean array efficiency in neutral and flexed spine models.
• Investigated methods to reduce spine-induced insertion loss, including array reconfiguration and lower frequency sonication (250 kHz).

Main Results:

• Both arrays produced controlled foci within the spinal canal with similar dimensions (axial: 10.8-11.9 mm, lateral: 4.2-5.6 mm, vertical: 5.9-6.2 mm).
• Spine flexion increased four-component array efficiency, while target-specific reconfiguration significantly improved efficiency.
• Lower frequency (250 kHz) sonication improved efficiency but widened lateral focal dimensions.

Conclusions:

• Simulations demonstrate the capability of spine-specific phased arrays to generate controlled foci within the thoracic spinal canal.
• The successful design of these arrays is vital for the clinical translation of focused ultrasound for spinal cord disease treatment.